ssl_cipher for mail not working

to increase security of SSL I added some eliptic-curves-ciphers to the chain. For HTTPS it's working fine, but for the mail proxy it does not work, I only always get RC4-SHA instead of the ECDH ciphers.See configuration at the end of this message.

The first command gives me a successful connection with ECDHE-RSA-RC4-SHA, so for HTTPS the cipherlist is used. The second command fails with an error: "sslv3 alert handshake failure", the IMAPS server does not provide ECDH support. I used exactly the same ssl_cipher line for HTTPS and the mail proxy.

When using the following command without forcing any ciphers on the client I can see that RC4-SHA is the "best" cipher that is supported and used:openssl s_client -connect imap.domain.de:993